> > Sealing the vent hole would prevent built up gases from escaping and probably would 
> > crack the case, allowing electrolyte to escape, essentially destroying the battery...
> > 
> > Jack
> > jackr@starfleet.scs.ag.gov
> > 
> 
> No, I meant the vent holes in the battery compartment. they vent to the
> outside of the van thereby letting cold air in..... -- 

Same answer.  Those gases have to go somewhere.  If you seal the vents to the outside
then they'll wind up in the passenger compartment.  I don't know about you but I
prefer oxygen over hydrogen when it comes time to breathe ;).

I can't tell from your original post why you think sealing the vent holes will do anything
for the battery.  The battery'll be the same temperature as the outside air after sitting 
overnight anyway.

Jack
jackr@starfleet.scs.ag.gov